by Rob Speer

The three metas give you these answers:

UNKNOWN TOOL

14-0637

DOOR INTO OFFICE OF DR BENOIT FORGET

You find an envelope containing a paper Enigma rotor in subbasement 9,
near the Tomb of the UNKNOWN TOOL.
It maps the alphabet to BPJLNTVWMYUXFQHZIOCKDGSAER, and the input letters
E, N, and I are marked with a gray background.

14-0637 is a room where you can find another rotor (on a handy cardboard
cylinder of the right size with an input wheel). The rotor maps the alphabet to
GHQDUIVPYABEFNRLSKCXTWMZJO. G, M, and A are marked with a gray background.

The last rotor is in an envelope on the DOOR INTO OFFICE OF DR BENOIT FORGET
(24-214). It maps the alphabet to MLEXBZSAIVDJNRTYOKFWQHGPCU, and no letters
are marked.

The metas and the supermeta intro give you all the pieces of a paper Enigma,
and you just have to figure out how to put it together. (NB: The inspiration for these rotors comes from the "paper Enigma" described here. The images used to create them can be found here.)

The example checks that you're advancing the rotors properly. You rotate the
rightmost rotor before decoding a letter. If the rightmost rotor has a mark lined
up with A on the input rotor, you rotate the center rotor as well. If the center
rotor has a mark lined up with A on the input rotor, you rotate all three rotors.

If you have all three metas, you just have to put the pieces together in the
correct order (trying up to 6 possibilities) and implement the right Enigma rules.
If you have two, you get to try to break an Enigma wheel from a lot of crib text.
(Random Thymes: "If the Brits could do it in the '40s, we can do it with an 8,000
core supercomputer!" They got the last meta before it mattered.)

Some pitfalls:

The rightmost wheel rotates before decoding. (On the physical machine,
the force of pressing a key causes it to rotate.)

It's tempting to think of the rotors as turning like an odometer, in which case
the left wheel would only turn if both other wheels were notched. But the WWII
Enigma (as well as Franklin Heath's
papercraft
Enigma) had a phenomenon known as "double-stepping", where the center wheel
would step again when it rotated onto a position with a notch that turns the left
wheel. If you don't do this, you get about 1/3 of the way through decoding the
answers and start getting gibberish.

The reflector does not rotate. Its A always lines up with A on the input wheel,
not on the left wheel. Unfortunately, the example does not check this, but you will
get complete gibberish as the decoding if you line it up with the leftmost wheel.